Vietnam's top diplomat arrived in North Korea on Tuesday for talks over a possible state visit by North Korean leader Kim Jong-un to the Southeast Asian country ahead of his second summit with U.S. President Donald Trump, a foreign report said.

Foreign Minister Pham Binh Minh, who doubles as Vietnam's deputy prime minister, flew into Pyongyang in the afternoon on a three-day visit, according to Japan's Kyodo News.

Other foreign media reported earlier that Minh boarded an Air Koryo flight bound for the North's capital city at an international airport in Beijing. He arrived in the Chinese capital on an Air China flight earlier in the day.

He was accompanied by five government officials, including the ministry's protocol chief, according to an informed source. Also in his entourage were Vietnamese journalists.

Kim Chang-son, a close aide to the North Korean ruler and director of the State Affairs Commission, was expected to visit Hanoi for consultations with Vietnamese authorities over protocol and other issues related to the leader's possible trip.

But Pyongyang has been selected as the venue for the discussions apparently due to easier security control.

"After the Vietnamese foreign minister finishes prior coordination with North Korean officials during his visit to the North, the North and the U.S. may have discussions over protocol issues in Hanoi," the source said.

Vietnam's Foreign Minister Pham Binh Minh(left) arrives in Beijing on Tuesday to head for North Korea. Yonhap

Earlier this week, the ministry's spokeswoman, Le Thi Thu Hang, wrote Monday on Twitter that he will travel to the North through Thursday at the invitation of his counterpart, Ri Yong-ho.

The North's leader is scheduled to meet again with U.S. President Donald Trump in Hanoi on Feb. 27-28.

Many observers bet that Kim will pay a state visit to Vietnam just before or after his meeting with Trump, which expected to focus on fleshing out Pyongyang's additional denuclearization steps and Washington's corresponding measures.

If Kim does so, he will be the first North Korean leader to visit the country in 54 years. Kim Il-sung, the country's late founder and grandfather of the current leader, visited Hanoi in October 1964.